Systems and methods for testing water for chemicals and other properties are known in the art. A prevalent method consists of inserting into the tested water an absorbent material, such as paper, which is impregnated with a chemical reagent. The reagent chemical is designed to react with predetermined chemicals or predetermined fluid properties. As a result of this reaction, the color of the reagent chemical changes, and this is visible on the absorbent material. Accordingly, a color change is achieved when the water under test, contains these predetermined chemicals or is characterized by the predetermined fluid properties. The hue of the resulting color can further quantitatively determine the level of the detected chemical or property, by comparing the hue with a standard color scale.
U.S. Pat. No. 3,876,378 to Montagnon, entitled “Analytic Device Utilizing Reaction-Sensitive Chemical Product”, is directed to an apparatus for chemical testing of liquids using a chemical reagent. The construction of this apparatus is intended to overcome some of the problems that may occur in such tests. The apparatus includes a vessel with a flange at its bottom forming a groove, and a disc made of absorbent material, which comfortably fits inside the groove. The disc is impregnated with a chemical reagent, so that upon introduction of the tested liquid, the disc may undergo a color change, depending on the conditions of the liquid.
U.S. Pat. No. 4,904,605 entitled “Method and Apparatus for Residential Water Test Kit” issued to O'Brien et al., is directed to a system and method for testing water for a plurality of chemicals and other characteristics. The water test kit includes a container with a label on the exterior. The label includes a color comparison chart and optionally, operating instructions. The color comparison chart indicates the properties to be tested. Each row of the chart pertains to one chemical or property, and includes a scale of colors and their corresponding levels of the chemical concentration or the property. The kit further includes a dipstick or test strip. The dipstick or test strip is divided into a plurality of areas. Each area contains a reagent that reacts to a specific chemical or fluid property, producing a color change in that area. To test the water using this device, the user first fills the bottle with tap water. She then fully immerses the test strip in the sample bottle and waits for 30 seconds. Next, she removes the test strip from the water, and positions the test strip so that it is aligned with the color chart. Finally, she compares the color of each of the test strip areas to the corresponding section of the chart.
Numbers indicating problematic levels are underlined and may also be printed in a different color (e.g., red) from the rest of the numbers on the chart. A solution chart may also be provided, on which solutions to the problems are given, possibly by reference to different water filters and the like. The need for the strip to be matched with the color chart makes this system relatively complicated to operate, and may result in misreadings or other errors by the unskilled user. It is also necessary for all of the separate parts of the kit to be present in order for the testing to be possible. Another method for colorimetric testing of water known in the art consists of inserting a reagent into the water sample and allowing it to react inside the water, thus causing the water to change color, and then comparing the color of the water with a standard color scale.
U.S. Pat. No. 3,381,572 entitled “Colorimetric Testing Device” issued to Tuwiner, is directed to a device for quantitatively determining the concentration of a chemical or the levels of a property such as pH. The apparatus includes an optical color index unit, adjacent to a container for the tested sample. The index unit color changes gradually from one end to another, in correspondence with the color change of the tested sample at different levels of the property being tested. The index unit also has numbers printed thereon to indicate the corresponding levels. To perform the test, the user inserts the sample, together with a color-indicating reagent, into the container and compares the changed color of the sample with the index unit color scale.
U.S. Pat. No. 4,125,376 entitled “Method for Detecting Water Pollutants” issued to Razulis, is directed to a method for identifying chemicals in water. The apparatus is a transparent container, with an urethane foam cube disposed therein, and a plug for sealing the tube. The urethane foam cube is impregnated with a specific spot detection chemical. The chemical produces a calorimetric indication when exposed to specific pollutants in the tested water sample. The method is carried out by adding the water to the container, sealing the container with a plug and then shaking it. The color change is then compared to a color comparator chart of the specific pollutants.
U.S. Pat. No. 4,180,009 issued to Voss et al., and entitled “Ion Concentration Testing Apparatus”, is directed to a device for determining different ion concentrations in swimming pool water. The device includes two measurement containers, a reference container and an indicating screen. The measurement containers and the reference container are bounded on one side by a common wall. The indicating screen is located in front of the common wall and includes a plurality of indicating windows associated with the measurement containers and a plurality of indicating windows associated with the reference container. The measurement containers and the reference container are arranged in a row and each has a square or a rectangular cross section. The indicating windows are distributed over the height of the measurement containers and the reference container. Each of the indicating windows associated with the reference container, has a reference or standard coloration corresponding to a predetermined ion concentration. The indicating windows are transparent.
The indicating screen further includes a plurality of marks adjacent to the indicating windows associated with the measurement containers. The value of each of the marks is related with the respective indicating window associated with the reference container. The user fills the measurement containers with water and inserts different color forming reagents, according to the particular ion concentration to be tested, in each measurement container. The color forming reagents dissolve and the water in each measurement container acquires a color which corresponds with the concentration of the ion. The user compares the color of the water seen through the indicating windows associated with a measurement container, with the respective reference coloration of the indicating window associated with the reference container. The user determines the ion concentration by reading the value of the mark, which corresponds with the reference coloration which was identified as a result of this comparison.
Merck KGaA located in Darmstadt, Germany, discloses a first method for determining the concentration of substances in water, landfills and soil. According to the first method, the user adds a liquid reagent to a liquid sample, thereby rendering a color to the liquid. The concentration of the substance is measured by a photometer, according to the color of the liquid. Merck KGaA discloses a second method for testing a solution. According to the second method, the user dips a test strip in the solution. After a given reaction time has elapsed, the user compares the color of the reaction zone with a color scale on the package, thereby determining the concentration.
Merck KGaA discloses a system for determining the concentration of substances or a parameter in a liquid. The system includes an electronic instrument, a plurality of test strips and a bar code. Each of the test strips are designated to test the concentration of a selected substance or a selected parameter in the liquid. The bar code includes information respective of the selected substance or the selected parameter. The user calibrates the electronic instrument, by passing the bar code through the electronic instrument. The user then dips a test strip in the liquid, whereby the reaction renders a color to the test strip. The user passes the test strip through the electronic instrument, the electronic instrument determines the value of the concentration or the parameter and displays this value on a display.
Hach Company located in Colorado, U.S.A., discloses a colorimetric method for determining the concentration of a parameter in a sample. The user adds a reagent to the sample, thereby rendering a color to the sample. The user determines the concentration by comparing the color of the sample with test strips, color cubes, color discs, a colorimeter or a spectrometer. Hach discloses an electrochemical method for determining the concentration of a parameter. According to the electrochemical method, the presence or the absence of a parameter is determined, by measuring the electrical activity of a sample. Hach discloses a titration method for determining the concentration of a substance. According to the titration method, the user dispenses a reagent on the sample, until the color of the sample changes. The user determines the concentration by measuring the volume of the reagent which is dispensed (e.g., by counting the drops of the reagent dispensed from an eye dropper, or according to the reading of a digital titrator).